that mark (Nick) on the lens is from the molding process, it is where the sprue was in the mold. The sprue is where the plastic gets pushed into the cavitity where the lens is formed, my guess there are several cavitity's (that's the most cost effect way to do production runs) in the mold and when they take them out it looks like a lens tree.
Remember when ya built models as a kid all the parts were attached to that plastic frame, thats a sprue.
